946
FXUS62 KKEY 280227
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
1027 PM EDT Sun Sep 27 2026

...New DISCUSSION, MARINE, AVIATION...

.KEY MESSAGES...

- Saltwater to major saltwater flooding of low elevation streets
  and lots is likely through this week due to a potent King Tide.
  Don`t drive through flooded roadways. Boaters can expect less
  clearance under fixed bridges.

- A Coastal Flood Advisory is in effect for the Lower to Middle
  Keys, and a Coastal Flood Warning is in effect for the Upper
  Keys.

- Northeasterly swell from a Nor`easter off the East Coast will
  continue to produce 2 to 4 foot seas through the overnight in
  the eastern Straits of Florida.

&&

.DISCUSSION...
Issued at 1027 PM EDT Sun Sep 27 2026
CIMSS products continues to show quite a complex pattern across
the Lower 48 and the western North Atlantic. There are literally 3
ridges all of which are blocking the current Nor`easter in the
vicinity of New Jersey from going anywhere. One ridge is across
the central North Atlantic with the second moving over the top of
the trough across New Brunswick, Canada and Maine area, and the
third ridge is across Mexico. At the surface, weak high pressure
remains in place across the Gulf, though, an interesting situation
unfolded this evening for the marine platforms off the Upper Keys.
Current thinking for the higher than expected wind speeds in this
area was due to a heat low that formed across South Florida. This
probably lead to lower pressure combined with the high over the
Gulf which created for a slightly higher pressure gradient and
resulted in higher wind speeds. Marine platforms surrounding the
Island Chain are recording west to northwest breezes of 5 to 10
knots with the exception of a very localized area in the vicinity
of Carysfort Reef Light which has been recording 15 to 20 knots
for the past few hours and only recently came down to 10 to 15
knots. This did warrant an update earlier to the coastals for the
eastern Hawk Channel for 10 to 15 knots which most of the area
was seeing, except Carysfort which locally was a little higher.
KBYX radar has not detected any shower activity through the
evening hours across the Keys. Temperatures along the Island Chain
are comfortable in the lower 80s and dew points are in the upper
60s.

.SHORT TERM FORECAST...
The 00z evening sounding continues to remain quite dry. However,
moisture is beginning to grow in the lower levels with a moist
layer from approximately 900 to 800 mb. The PWAT value measured
was 1.34 inches which is right at the 10th percentile for the
date. The wind profile is mostly unidirectional out of the west at
near 10 knots. Overall, no forecast changes are expected this
update and shower activity, if any, is mainly expected to remain
across the marine area, especially south of the Chain.

&&

.MARINE...
Issued at 1027 PM EDT Sun Sep 27 2026
There are currently no watches, warnings, or advisories in effect
across the Florida Keys coastal waters. From synopsis, a
Nor`easter in the vicinity of New Jersey which will continue to
support a northeasterly swell with large periods in the eastern
marine zones through overnight, before subsiding tomorrow. A weak
frontal boundary will begin to push back northward through the
marine zones on Monday. Winds will then clock back to the
southeast to south for early this week, also accompanied by
increasing rain and thunder chances. In addition, strengthening
high pressure is expected to move off the Southeast U.S. coastline
around the middle to latter half of next week, merging with the
Atlantic high. This will promote freshening east to southeast
breezes, potentially become moderate to fresh.

&&

.AVIATION...
(00Z TAFS)
Issued at 1027 PM EDT Sun Sep 27 2026
VFR conditions will persist at both EYW and MTH terminals through
the TAF period. Near surface winds will remain west to northwest
overnight, shifting to the southwest to west Monday morning before
further shifting to the south to southwest Monday afternoon and
evening. Near nil rain chances are expected through the TAF
period, though, there is a very low risk for a passing shower
sometime Monday afternoon or evening that could affect either
terminal.

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  87  77  88  77 /  10  10  30  60
Marathon  85  78  86  78 /  10  10  20  60

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...Coastal Flood Warning until 6 AM EDT Monday for FLZ076.

     Coastal Flood Advisory until 6 AM EDT Monday for FLZ077-078.

GM...None.
&&

$$

Public/Marine/Fire...MJV
Aviation/Nowcasts....MJV
Data Acquisition.....PV/DR

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